I like this New Yorker article on why New York is the greenist city. Here’s a clip:
By helping us to live at greater distances from one another, driving has undermined the very benefits that it was meant to bestow. Ignacio San Martín, an architecture professor and the head of the graduate urban-design program at the University of Arizona, told me, “If you go out to the streets of Phoenix and are able to see anybody walking—which you likely won’t—they are going to tell you that they love living in Phoenix because they have a beautiful house and three cars. In reality, though, once the conversation goes a little bit further, they are going to say that they spend most of their time at home watching TV, because there is absolutely nothing to do.” One of the main attractions of moving to the suburbs is acquiring ground of your own, yet you can travel for miles through suburbia and see no one doing anything in a yard other than working on the yard itself (often with the help of a riding lawnmower, one of the few four-wheeled passenger vehicles that get worse gas mileage than a Hummer). The modern suburban yard is perfectly, perversely self-justifying: its purpose is to be taken care of.